Developing fuels

Question 1

What is meant by organic chemistry

Answer 1

the study of the structure, properties, composition, reactions, and preparation of carbon-containing compounds.

Question 2

How many bonds does each carbon atom typically form in an organic molecule?

Answer 2

4

Question 3

What should the ‘full structural formula’ of a molecule look like? (e.g. pentane)

Answer 3

have bonds and elements shown
H H H H H
| | | | |
H-C-C-C-C-C-H
| | | | |
H H H H H

Question 4

What should the ‘skeletal formula’ of a molecule look like? (e.g. pentane)

Answer 4

Only carbon bonds shown, Carbons are represented by ends

/\/\

Question 5

What is the definition of a ‘hydrocarbon’ compound?

Answer 5

compound only made up on hydrogen and carbon atoms

Question 6

What is the definition of a ‘saturated’ compound vs. an “unsaturated’ compound?

Answer 6

saturated compounds have no C=C bonds

Question 7

What is the definition of an ‘aliphatic’ compound vs. an ‘aromatic’ compound?

Answer 7

aliphatic has no benzene rings

Question 8

What structural features do all ‘alkanes’ have in common?

Answer 8

-only have single bonds
-hydrocarbon

Question 9

What is the ‘general formula’ of an alkane?

Answer 9

CnH2n+2

Question 10

What chemical test can be used to show that the cracking process has been successful?

Answer 10

Bromine water turns from orange to colourless

Question 11

What effect does catalytic cracking have on a long chain alkane molecule?

Answer 11

• break a long chain alkane into shorter alkene(s) and an alkane

Question 12

What is meant by a ‘sigma’ bond in a molecule

Answer 12

two of any orbital with an unbonded electron colliding head to head

Question 13

What is meant by a ‘pi’ bond in a molecule

Answer 13

two p orbitals with an unbonded electron colliding side to side parallel with the internucli axis

Question 14

In terms of sigma and pi bonds, what does a double covalent bond consist of?

Answer 14

a single sigma bond

Question 15

What is the general definition of a catalyst?

Answer 15

a substance that is not used up that lowers the activation energy of a reaction by proving an alternative pathway

Question 16

Which is stronger – a sigma bond or a pi bond? Explain.

Answer 16

sigma- on the internucli axis- stronger electrostatic forces of attraction- more energy to break

Question 17

How can you tell from a balanced equation that something used as part of a process is probably a catalyst?

Answer 17

same on both sides of the equation

Question 18

What is meant by a homogeneous catalyst?

Answer 18

catalyst that is in the same state as the reactants

Question 19

What is meant by a heterogeneous catalyst?

Answer 19

catalyst that is a different state as the reactants

Question 20

What are the steps in the mechanism by which a heterogeneous catalyst functions?

Answer 20

reactants bond and adsorb to the catalyst surface

Bonds in reactants weaken an break

Nee bonds form, creating the product

the product desorbes from the surface and diffuses away

Question 21

How do a catalyst ‘poison’ decrease the effectiveness of a heterogeneous catalyst?

Answer 21

reacts with catalyst surface, blocking the reactants from adsorbing, reduces available for adsorption
catalyst reduces in activity

Question 22

What chemical test can be used to show that the cracking process has been successful?

Answer 22

bromine water added goes from orange to colourless

Question 23

what is the equation for the removal of CO and NO

Answer 23

2 CO(g) + 2 NO (g) —> 2CO2(g) + N2(g)

Question 24

Explain the energy change in breaking bonds in terms of endothermic and exothermic processes

Answer 24

breaking bonds requires energy from surrounds, so is an endothermic process

forming bonds releases energy into surroundings, so is ab exothermic process

Question 25

Explain what makes a reaction endo/exothermic

Answer 25

if the enthalpy change is positive, and the surrounding temperature has decrease, this is because the energy required to break bonds is higher than the energy released by forming bonds and the reaction is endothermic.